Antidysrhythmic Toxicity Medication

Updated: Jun 27, 2016
  • Author: Nidhish Sasi, MD; Chief Editor: Asim Tarabar, MD  more...
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Medication

Medication Summary

Discontinuation of the precipitating drug is of paramount importance. Gastrointestinal decontamination is empirically used to minimize systemic absorption of the drug. Hemodialysis may be indicated in certain drug toxicities as well as targeted antitidotal therapies.

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Antidotes, Other

Class Summary

GI decontamination with oral activated charcoal is selectively used in the emergency treatment of poisoning caused by some drugs and chemicals.

Activated charcoal (Actidose-Aqua, EZ-Char, Kerr Insta-Char)

Activated charcoal is used in emergency treatment for poisoning caused by drugs and chemicals. A network of pores adsorbs 100-1000 mg of drug per gram. Multidose charcoal may interrupt enterohepatic recirculation and enhance elimination by enterocapillary exsorption. Theoretically, by constantly bathing the GI tract with charcoal, the intestinal lumen serves as a dialysis membrane for reverse absorption of drug from intestinal villous capillary blood into intestine.

Activated charcoal achieves its maximum effect when administered within 30 minutes after ingestion of a drug or toxin. However, decontamination with activated charcoal may be considered in any patient who presents within 4 hours after the ingestion.

Repeated doses may help to lower systemic levels of ingested compounds, especially sustained-release preparations. Activated charcoal does not dissolve in water. Supply it as an aqueous mixture or in combination with a cathartic (usually sorbitol 70%).

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Electrolyte Supplements, Parenteral

Class Summary

Potassium and magnesium should be repleted in patients taking QTc-prolonging drugs. High doses of magnesium may decrease the risk of QTc prolongation during ibutilide infusions.

Calcium chloride

Calcium is given to reverse hypotension and improve cardiac conduction defects. Calcium chloride theoretically increases calcium's concentration gradient, overcoming the channel blockade and driving calcium into the cells. It moderates nerve and muscle-performance by regulating action potential excitation threshold.

Magnesium sulfate

Magnesium acts as an antidysrhythmic agent and diminishes the frequency of premature ventricular contractions (PVCs), particularly those resulting from acute ischemia. Deficiency in this electrolyte can precipitate refractory ventricular fibrillation (VF) and is associated with sudden cardiac death. Magnesium supplementation is used for treatment of torsade de pointes, known or suspected hypomagnesemia, or severe refractory VF.

Sodium bicarbonate (Neut)

Intravenous sodium bicarbonate can be life saving in patients presenting with cardiotoxicity from antidysrhythmics with sodium-channel blocking properties and QRS widening. Sodium bicarbonate can be given as 1-2 mEq/kg (typically 100 mEq) as a bolus, followed by continuous infusion if the QRS narrows after bolus infusion. A 12-lead EKG should be run while administering the sodium bicarbonate bolus to ensure that QRS narrowing isn't missed because of a delayed EKG. Serum pH should be monitored if a sodium bicarbonate infusion is used. 

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Alpha/Beta-Adrenergic Agonists

Class Summary

Vasopressors are indicated for persistent hypotension not responsive to judicious fluid loading and sodium bicarbonate.

Norepinephrine (Levophed)

Norepinephrine has strong beta1- and alpha-adrenergic effects and moderate beta2 effects, which increase cardiac output, blood pressure, and heart rate, while decreasing renal perfusion and pulmonary vascular resistance

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Beta1/Beta2 Adrenergic Agonists

Class Summary

These agents may be used to treat symptomatic arrhythmia.

Isoproterenol (Isuprel)

Isoproterenol is used to treat torsade de pointes if magnesium supplementation fails to treat it. It is also used to treat ventricular tachycardia or fibrillation in the setting of Brugada syndrome.

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Anticonvulsants, Other

Class Summary

By increasing the action of gamma aminobenzoic acid (GABA), a major inhibitory neurotransmitter, benzodiazepines may depress all levels of the central nervous system (CNS), including the limbic system and the reticular formation.

Diazepam (Valium, Diastat)

Diazepam depresses all levels of the CNS (eg, limbic system and reticular formation), possibly by increasing the activity of GABA. It is a third-line agent for agitation or seizures because of its shorter duration of anticonvulsive effects and the accumulation of active metabolites that may prolong sedation.

Lorazepam (Ativan)

Lorazepam is the drug of choice for treatment of status epilepticus because persists in the CNS longer than diazepam. The rate of injection should not exceed 2 mg/min. This agent may be administered intramuscularly if vascular access cannot be obtained.

Midazolam

Midazolam is an alternative agent for termination of refractory status epilepticus. Compared with diazepam, midazolam has twice the affinity for benzodiazepine receptors; however, because it is water soluble, midazolam takes approximately 3 times longer than diazepam to achieve peak electroencephalographic effects. Thus, the clinician must wait 2-3 minutes to fully evaluate sedative effects before initiating a procedure or repeating the dose. This agent may be administered intramuscularly if vascular access cannot be obtained.

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